Stepper motors enable precise positioning operations, and so they are used when high accuracy is required for demanding positioning tasks. They consist of a stationary stator and a rotor rotating inside it, which is driven by torque generated by differently aligned magnetic fields in the stator and rotor. The rotor always turns in such a way that the greatest possible magnetic flux is created. Stepper motors are primarily used in factory automation, but are also increasingly being used in machine and plant building.
Stepper motors are characterised by a very high torque at a low rotational speed. This enables the application to be both started quickly and – thanks to the high holding torque – to be stopped easily too. The direction of rotation can also be changed quickly and at any time. Other important advantages of stepper motors are the high accuracy they offer during operation and the easy monitoring of the rotor position. In addition, stepper motors do not have brushes, which contributes significantly to the high mechanical resistance of the application.
Basically, there are three different types of stepper motors: the reluctance stepper motor, the permanent magnet stepper motor and the hybrid stepper motor. The latter combines the properties of reluctance and permanent magnet stepper motors and is thus the most efficient of the three versions. Hybrid stepper motors have a stator with stator poles with multiple teeth and a rotor consisting of up to 200 teeth that can move at step angles of 1.8° each. Hybrid stepper motors have a high static and dynamic torque as well as a very high stepping speed and are therefore used in numerous applications, including PC drives and printers. The main application areas for hybrid stepper motors in industry are machine tools and handling machines.
Festo uses hybrid technology in the further development and production of stepper motors. The stepper motor EMMS-ST is part of our Core Range and is ideally suited for simple positioning applications. The EMMS-ST enables a small step width at high driving torques, has optimised connection technology and is available in four sizes with flange dimensions 28, 42, 57 and 87. It is also optionally available with a holding brake.